1. Field of the Invention
The present invention relates to an artificial satellite that is launched into space aboard a rocket to allow communications with the ground and observations of the earth.
2. Description of the Related Art
In the beginning of space development, artificial satellites were each a developed product. They were all designed and developed from the beginning and launched aboard a rocket. At that time, each individual component and part was improved gradually in view of the results of the launch, and the artificial satellites themselves or their partial constituting elements could not be standardized unlike general industry products. In other words, the artificial satellites were manufactured one by one, which increased their costs and lengthened their development period.
In the latter half of the 1970s, a communications satellite was coming to the fore as the principal mission of an artificial satellite. In the age when demand for communications increased and private companies owned artificial satellites, a number of communications satellites were launched.
The communications satellites had a system unit called a bus unit almost in common as one of requests to the artificial satellites. The bus unit could be designed as a common one, and only the function units (mission equipment units) could be designed and developed individually at user's different requests.
Since the bus units of the satellites were almost standardized, the development and manufacturing costs of the artificial satellites could be decreased and the development period thereof could greatly be shortened. The makers and users of the artificial satellites could therefore obtain a lot of benefit. For example, Hughes Aircraft Company that adopted this system achieved huge success and the basic idea of the system continues until today.
As an example of a prior art artificial satellite designed and manufactured individually, an engineering test satellite No. 6 (made in Japan) is known, as disclosed in Masamichi Shigehara and Yoshio Toriyama, “Introduction to Design of Satellites,” Baifukan Co., Ltd., Jun. 13, 2002, p. 82, FIG. 3.6. This is an artificial satellite that is a box-shaped structure including a mission panel and an access panel, which are honeycomb sandwich panels. The structure includes a solar panel, an antenna module and a communication device.
As a module-type artificial satellite, a satellite whose common unit called a bus unit is standardized and whose mission (targeted function unit) is manufactured to order is known, as disclosed in The Japan Society for Aeronautical and Space Sciences, “Handbook for Aeronautical and Space Engineering,” Maruzen Co., Ltd., Sep. 30, 1992, p. 840, Table C1.14 and P. 841, FIG. C1.22.
A module-coupled type space structure and an attitude control method are known as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-264299. A module-system spacecraft developing method is known as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-226399. A module-system spacecraft backbone interface is known as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-210057. A module-system spacecraft structure is known as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-203494.
A huge success was achieved by standardizing the bus units of artificial satellites chiefly including communications satellites using the method described above. Paying attention to generally used artificial satellites including earth observatory satellites, however, the artificial satellites are difficult to standardize in view of a large variety of requests for functions and performance of the artificial satellites, and are manufactured one by one. High costs and long periods for developing the artificial satellites still remain unchanged.
The reason for the above is as follows. It is a relay that is mainly loaded on a communications satellite, and there is no big difference in request for functions between communications satellites. In contrast, a generally used artificial satellite may include a radar and TV broadcasting equipment using power that is higher than that of the satellite. Some artificial satellites loaded with a special observation machine are particularly strict with an attitude control system. In order to develop a satellite having various function requests, a standardized bus developed chiefly for communications satellites is difficult to use, and any cost advantage cannot be obtained.
The artificial satellites disclosed in the above publications “Introduction to Design of Satellites” and “Handbook for Aeronautical and Space Engineering” are complicated in structure and large in size and cannot be folded compact. They cannot be therefore loaded into a small-sized rocket.
These publications 1 to 4 disclose a module-system structure and a module-coupled structure and none of them disclose any technical concept of combining a plurality of modules (panels) having different functional elements.
The present invention provides an artificial satellite which can be folded compact when it is launched aboard a rocket and whose functions, performance and capacities can be extended and reduced at user's requests to thereby decrease its costs and shorten its development period.